Restore from backup and backup status

[former_member199632]

Hi,

We are getting 2 backups from PRD system

Backup Option 1: Online Backup, while the DB is up and running  -  (DB Files + Archived logs + Online redo logs) - Backup Time: 6.00pm

Backup Option 2: Split mirror backup (SMB)  - (DB Files Only)  - Backup Time: 5.00am

(Backup is getting from the business copy volume, while the system is up and running from the Primary Volume)

Since DB is up and running , backup "Backup Option 1", can be mentioned as inconsistent backup

-> I want to know is this SMB backup "Option 2" status? (Is it a consistent backup OR is it a inconsistent backup)

-> Is it possible to restore a database with mix of files from an inconsistent backup and consistent backup ?

(For example: 07 datafiles from "Backup Option 1"  and 05 datafiles from "Backup Option 2")

Just assume a situation like this;;

The PRD crash @ 11.00am in the morning

Now we having 2 backups;

Online Backup from previous day 6.00pm (17hrs old)  AND   that's days SMB backup @ 5.00am (6hrs old)

Kindly clarify me, what is the most suitable backup to recover and restore the system

regards,

zerandib

[Former Member]

Hi,

Ans 1 ) I think it cannot be termed that the backup is consistent or inconsistent in the
        case of SMB as you would have a crash copy of the database when the DB crashes.
        In this case , if you wish to bring the database up then you can simply restore
        the files and then bring up the database. I think SMP takes care of the fractured
        blocks, corrupt blocks etc. So, the database can be restarted but you would only
        have the data until the time when the DB crashed.

Ans 2)  No, it is never the  recommended way to have a restoration  from a mix of backups .
      

To the scenario that you have  described for the PRD crashing at 11 AM It should be good to go ahead with the restoration from SMP as in the case of the online backup restoration , it would again ask for the archivelog files to bring the datafiles into consistent state. But in case of SMP you can simply restore the datafiles and open the database but in this case you would have the data till 5 AM .Again ,to get to 11AM you would again need to apply all the archivelog files .  Please remember that the DB should not be opened after the restoration but should be opened in mount state and then all the archivelog needed being in the archivelog destination , Recover the database using ultil SCN,until time or until sequnece number and then you can open the database using open resetlogs.

[former_member199632]

Hi Faizuddin,

thx for the explanation.

Is it possible to apply archive logs to the SMB;

(We surely can apply archive logs to online backup; But im confuse is this SMB online or offline)

yes in that case restore from SMB backup is the good option for this scenario

I have another point to clarify. Is it possible to apply archived logs to a backup taken from shuttling down DB.? (Apply archived logs to an offline backup?)

For example;  Get a DB backup @ 1.00 am by shutting down the DB (Consistent backup)

At 10am , there are newly created 7 archived log-files

Is it possible to apply those newly created log-files in to the earlier backup which took @ 1am, and the DB in to the new state

thanks

[Former Member]

Dear Zerandib,

SMP is split mirror disk backup . You can have more details of SMP from the below link -:

http://help.sap.com/SAPHELP_NW04s/helpdata/EN/68/b72d86db13c642bb6e17b83b75f598/content.htm

To answer the second question -:

I have a production database . The major priority here is no data loss , availability  etc .  Looking at the No data loss priority -:

I have taken an offline backup yesteday around midnight( 11:30 PM ) . The database is open now and working fine . Where are the changes being made to the database recorded ? -> Redo logfiles ( which eventually goes to )  archivelog files and also the changes are made to the coresponding datafiles.

If the database crashes at 1 PM today then I have only one backup i.e offline backup . I restore the datafile with this backup ( This would mean that the datafiles have the image upto 11:30 PM yesteday ). If I try to open the database , I would loose data from the time when the database was again brought up after taking the backup which was  triggered at 11:30 PM yesterday  tiil the time when the DB crashed.

Now from where do I get the record of changes made . The only option here is archivelog files .